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Run Live Demo

To run UltimateSLAM, you need an event camera with a hardware-synchronized inertial measurement unit. We have successfully tested UltimateSLAM with the DAVIS240C and DAVIS346 cameras.

Install DAVIS ROS driver

Before doing so, make sure to follow the instructions here to install any dependencies. In particular, make sure libcaer is installed. Then,

  • Build the DAVIS ROS driver:

catkin build davis_ros_driver

  • An update of the udev rules is needed to run the driver:
source ~/uslam_ws/devel/setup.bash
roscd libcaer_catkin
sudo ./install.sh

More detailed instructions are available here in case you are having troubles during this step.

Calibrate your DAVIS camera

Before running UltimateSLAM, you will need to calibrate your DAVIS sensor, i.e. estimate the camera intrinsic parameters, the camera-to-IMU extrinsic parameters, as well as the time offset between the IMU and the events. Some guidance is provided in this page.

Note that an accurate camera calibration is absolutely essential to get good tracking results. Make sure you treat this step with particular care.

Once you have performed calibration, copy your calibration file in the right format into the calibration folder.

Run UltimateSLAM live demo with the DAVIS

To run UltimateSLAM live with a DAVIS sensor, you will need to open multiple terminals at the same time. We recommend using Terminator, which allows to easily have multiple terminal windows open at the same time and easily navigate between those windows.

Open three terminals, and launch the following commands.

Terminal 1

Start a roscore:

roscore

Terminal 2

Start the DAVIS driver:

rosrun davis_ros_driver davis_ros_driver

Terminal 3

Start UltimateSLAM:

Events + Frames

roslaunch ze_vio_ceres live_DAVIS240C.launch camera_name:=<your_camera_calibration_filename> timeshift_cam_imu:=0.0028100209382249794

Events only

roslaunch ze_vio_ceres live_DAVIS240C_events_only.launch camera_name:=<your_camera_calibration_filename> timeshift_cam_imu:=0.0028100209382249794

The calibration file will be searched for in the calibration/ folder. In both cases, a new RVIZ window should pop up, showing the current camera position, trajectory and current estimated point cloud.

Parameters
  • camera_name: replace with the name of your calibration file in the calibration folder, without the .yaml extension.
  • timeshift_cam_imu: temporal offset between the camera and IMU. Please replace the value above with the one estimated by Kalibr during the calibration step.
  • frame_size: number of events to integrate in each event frame
  • motion_correction: if 1, will perform motion correction. Otherwise, not.
  • there are additional parameters in the launch files, please refer to the parameter tuning guide for more details.

Important advice

  • Initialization is fairly sensitive in UltimateSLAM. For best results, we advise to start with the sensor static (e.g. resting on a table). After launching UltimateSLAM, perform a few seconds of translational motion (moving left-right, up-down) with the sensor to get a good initial estimate of the IMU biases. Avoid initializing UltimateSLAM with the sensor already moving. Avoid initializing while doing mostly rotational motion with the camera.
  • As with any visual-inertial odometry system, a good calibration is of paramount importance to get good tracking results.
  • Proper parameter tuning is necessary to obtain the best results. By default, the parameters are set to work well with the DAVIS240C (240x180) sensor, and a moderate amount of texture in the scene.